The Irish Free State constitution was adopted by an act of Dáil Éireann and given royal approval in December. It established many of the articles that had been set out in the Anglo-Irish Treaty of 1921.

Northern Ireland (Unionists) opted out of the Irish Free State, and under the terms of the Anglo-Irish Treaty, this triggered the need for a Boundary Commission to determine the borders of the Irish Free State.

This period was marked by a series of atrocities by both sides in the Civil War. The war eventually came to an end in April 1923 with the leader of the Anti-Treaty Irish Republican Army telling his followers to no longer pursue a war that couldn’t be won. The first election under the constitution of the Irish Free State was held in August 1923.